A top-hung casement window can be opened outward horizontally and opened in a hanging manner as well. On a top-hung casement window in the prior art, a top-hung turning assembly is mounted at the upper edge of a window to implement turning and hanging operation of the casement sash; and a side-hung backward turning assembly is mounted at a bottom of the window sash and frame to implement closing operation on the opened sash.
As shown in FIG. 1, the top-hung turning assembly includes a turning block 10, a turning block slot 101, and a five-link sliding support 20. The turning block 10 cooperates with the turning block slot 101 to form a hinge structure; the turning block slot 101 is fixedly connected to an upper edge of the window frame; the turning block 10 goes through the turning block slot 101 and is fixedly connected to the top surface of the five-link sliding support 20; the bottom surface of the five-link sliding support 20 is fixedly connected to the upper edge of the casement sash; the turning block 10, the turning block slot 101, and the five-link sliding support 20 are connected by using a screw 30. The turning block 10 is mounted at the upper edge of the window frame, and can rotate around the turning block slot 101 relative to the window frame. The five-link sliding support 20 is mounted at the upper edge of the window edge to implement turning when the casement sash is top-hung. The casement sash is hung by using the turning block slot 101 and the turning block 10.
As shown in FIG. 2, the side-hung backward turning assembly includes the five-link sliding support 20 and an inclined shear bar 40, where the five-link sliding support 20 is mounted at a lower edge of the window frame and the inclined shear bar 40 is mounted at the lower edge of the casement sash. The five-link sliding support 20 and the inclined shear bar 40 are riveted so that they can rotate.
When the casement sash is open, the five-link sliding support 20 in the top-hung backward turning assembly and the five-link sliding support 20 in the side-hung turning assembly bear the casement sash and enable the casement sash to slide around the window frame at an angle of 90 degrees. However, to ensure that the casement sash can be turned when the casement sash is top-hung, the five-link sliding support 20 have to swing slightly up and down in vertical direction; otherwise, the casement sash cannot be opened in top-hung position to a certain angle. Therefore, in the structure of the top-hung backward turning assembly, the casement sash is unstable in a hanging position and will shake easily. In addition, due to heavy force of gravity, the casement sash presses the five-link sliding support 20 in the side-hung turning assembly and thus the casement sash is easy to droop down. Consequently, the casement sash is more and more difficult to be opened and closed, friction force increased, and components contacting the five-link sliding support 20 are abraded, while noise is generated, shortening the life span of the product.